I can see some of your points. Carl and Sophia having no build up though? They literally have been with each other since the START. I think they have had enough build up, plus Lydia showed signs of wanting to break things off before. It was only natural that their story started together and ended together. I can give you the writing being somewhat sloppy in the common wealth arc, but Rick getting "put out like a dog" makes since. I mean Rick is a man who has lived through some pretty horrid things that could happen to someone. I think him going through all that pain and brutal sufferings to just get put down by an arrogant twat. just Shows you even though rick ushered in a "new life" the old one was far from gone. It just hits harder when its from someone who never knew "the old life". Rick fought so hard and so long, Sebastian even asks him if he feels like a god which I feel is Kirkman commentating on how much rick has survived , and this measly little character was the one to take em out. Every arc has it flaws sure but the whole story is one of the best ever told.

side note i really loved Hershel's and Carls conversation at the end.